In the same way as humans, cats have binocular vision. This means that part of each eye has a field of vision that overlaps with that of the other eye. If the fields of vision of both eyes did not overlap, it would be impossible for cats to see three-dimensional images. For a hunting animal like the cat, binocular vision is important because it needs to be able to first spot its prey and then to judge the distance accurately when it goes in for the kill.
Contrary to popular opinion, cats cannot see any better in the dark than we can. However, they can see better in the dimmest light. At the back of a cat’s eyes there is a light-reflecting layer called the tapetum lucidum which acts like a mirror behind the retina, reflecting light back to the retinal cells which enhances the eye’s power of vision.
Cats can control how much light enters their eyes by reducing their pupils to vertical slits. So when light is very strong, cats can protect their eyes by narrowing their pupils and limiting the amount of light going into the eye. They can also use their eyelids to reduce the light input. This why a cat’s eyes close almost entirely in bright sunlight.
The cat has many visual assets which are important to it both as a predator and as potential prey itself. The cat’s eyes are certainly one of its most striking features being very large in relation to its skull. Positioned on the front of the head, they give a wide visual field (295 degrees) compared to that of humans (210 degrees).
Cats also have binocular vision which means that part of the field of vision of each eye overlaps. This overlap creates a stereoscopic effect so that three-dimensional impressions can be made.
Cats have a slightly wider binocular field than humans; human vision has 120° of binocular overlap, while a cat has 130° of binocular overlap. Dogs have an even lower binocular overlap than cats and humans, of between 80 and 110°.
- The cat’s frontal, three-dimensional vision is very important for it as a hunter because it helps it to gauge distances properly when stalking potential prey.
- Cats cannot judge distances as well as humans, but they can gauge them better than dogs.
- The human field of vision is not as comprehensive as that of the cat, but we compensate for this by being able to make far wider ranging eye movements due to the larger area of the white fibrous membrane, or sclera, around the iris.
- Cats are able to see moving objects better than stationary ones, which explains why cats often freeze when they are hunting.
- One way in which cats’ eyes are inferior to human eyes is that they cannot distinguish between some colours.